Rack for holding offset master sheets



' July 24, 1951 F, H, DAVIS 2,561,501

RACK FOR HOLDING OFFSET MASTER SHEETS Filed May 12, 1949 2 Sheets-Sheet 1 INVENTOR. FRED H. DAV/s Patented July 24, 1951 UNITED STAT RACK FOR HOLDING OFFSET MASTER 1 snnrrrs' n Fred H. Davis, Hamilton Ohio Application May 12, 1949', Serial No. 92,7 1

This invention relates to a rack adaptedfor holding an offset master sheet or the like during treatment such as cleaning, preserving, or developing the master.

In one type of offset printing, copy is setup on a flexible master sheet. The copyis inked and the inktransferred to an offset roll which i does the actual printing. Master sheets,which f may be made of thinfi exible sheet material such f as zinc, aluminum, paper or plastic, may be cleaned and reused. However, the cleaning process requires sponging of the copy surface with appropriate solvents, and during sponging the master sheet must be heldflrmly at both ends.

An object of this invention is to provide a rack constructed to hold an offset master sheet vide a rack having clamps adapted to engage during sponging or other treatment.

A further object of this invention, is to proboth ends of a master sheet to hold the master during sponging.

i sheet flat and smooth during treatment.

In the use of photo-sensitized masters, it is necessary to sponge a sensitized surface with appropriate photographic developers, and a further M object of this invention is to provide a rack for holding a photo-sensitized offset master sheet The above and other objects and features will in part be obvious and will in part be apparent from the following detailed description and the drawings, in which:

Figure 1 is a view in side elevation showing a rack constructed in accordance with an embodiment of this invention;

Fig. 2 is a bottom plan view of the rack illustrated in Fig. 1; n

Fig. 3 is a fragmentary view in side elevation showing the rack with a clamp plate thereof in released position; and

Fig. 4 is a view in end elevation of the rack.

In the following detailed description and the drawings, like reference characters indicate like parts.

As shown in the drawings, the rack includes a pair of flat panels In having adjoining edges hinged together by hinges I2. A free end [3 of each panel is bent at an obtuse angle thereto to form a supporting member. Buttons l4 of rubber or the like are attached to the support members 13 by means of angular legs I 6, and the buttons l4 serve to support the panels.

A clamp plate I1 is hinged at the free edge of each support member l3. Each clamp plate includes a main section [8 and a flange I9. Each flange I9 is adapted to swing toward one of the Claims. (Cl. 101 -131) panels 10 to grip an offset master sheet along an edge thereof asshown in Fig. 1. A handle" 2| the plane of the clamp plate.

is welded or otherwise firmly attached to each clamp plate for raising the clamp plate from the panel I0.

Each clamp plate is further provided with a pair of lugs 22 extending substantially perpendicularly to the plate, a lug being located at each side of the clamp plate and being formed from a section of the clamp plate bent away from The lugs 22'extend through slots 23 in the support members, and the lugs of oppositeclamp plates are joined by links 24. As shown inFigs. 1 and 3, the panels Ill meet in a peak at the hinges l2, and the panels and links 24 form a toggle linkage. When hinges H! are pushed towards links 24 to place the panels 10 in alignment, the clamps are pulled tightly against the edges of the offset master sheet to hold the master sheet firmly in place in flatwise relation upon the panels.

When the master sheet 20 is held in place upon the panels I 0, it is firmly held at bot-h ends and may readily be sponged with appropriate cleaning fluids, chemical developers or the like. ,The hinges [2 as shown in Fig. 1, are so formed that when the panels approach alignment, the hinges bind to prevent the toggle linkage formed by panels dead center. n f; The rack may be readily constructed of sheet In and links 24 passing metal parts or the like, and the clamp plates l1 are preferably formed of resilient metal so that when the panels are pushed toward aligned position, the clamps resiliently grip the edges of the master sheet, and as pressure on the panels is increased, the grip is tightened.

The embodiment of the invention described above and illustrated in the drawing is subject to structural modification without departing from the spirit and scope of the appended claims.

Having described my invention, what I claim as novel and desire to secure by Letters Patent is:

1'. A rack for holding offset master sheets which comprises a pair of adjoining fiat panels, adjacent edges of said panels being hinged to each other, a support member attached to the free end of each panel, said support members being adapted to support the panels, a clamp for jeach support member, each clamp including a pivot arm hinged to one of the support members .and a clamp arm adapted to engage one of the panels and grip an offset mastersheet along an edge thereof, and a link connecting said clamps, said panels being angularly inclined to each other when said clamps are open, the connection between each clamp and the link being between the panel hinge and the clamp pivot, the

' link pulling said clamps against the panels when the panels are moved into straight line position, whereby the clamp arms are adapted to grip opposite edges of the master sheet and hold the master sheet in flatwise relation to the panels.

2. A'i'rack for holding ofiset :master sheets which-comprises a pair of adjoining flat panels, adjacent edges of said panels being hinged to each other, a support member attached to the free end of each panel, said supportmembers being adapted to support the panels, a clampfor each support member, each clamp including a pivot arm hinged to one of the support members and a clamp arm adapted to engage one of the panels and grip an offset master sheet along'anedge thereof, and a link connecting said-clamps,

,said panels being angularly inclined to each ether-whensaid clamps are open, the connection :between each clamp and .the link being between the panel hinge and the clamp pivot, the link ,pnlling saidclamps against the panels when the panelsare moved into straight-line position, whereby the clamp arms are adapted togrip op- -posite edgesof the master sheet and hold the ;.'master sheet in flatwise relation to thepanels, the'hinge between .the panels being adapted to bind when the panels are in alignment to limit downward displacement of the panels.

.3. A rack for holding an offset master sheet which comprises -a .pair of adjoining .flat panels,

vadjacent edges of said panels normally meeting at apeak and being hinged to each other, a support member attached .to the free end of each panel and extending vat an obtuse angle to :the panel, said support members being adapted to support the panels, a clamp for each support .,-member, each clamp including a pivot arm hinged to one .of the support members and a clamparmadapted to engage one of the panels and grip an ofiset master sheet along an edge thereof, each of said clamps beingflformed of resilient metal, and a link connecting said clamps, the connection between each =clamp and the link being between the panel hinge and the clamp pivot, said panels being angularly in- .clined to each other whensaid clamps are open,

said link pulling the clamps against the panels when the .panels are moved into straight line ,position, whereby the clamp arms are adapted to grip opposite edges of the master :sheetre- .silien'tly and .hold the master sheet .in flatwise relation to the panels.

.4. A rack for holding an ofiset master sheet which comprises a pair of adjoining flat panels, .adjacent edges of said panels normally meeting at apeak andbeing hinged to each other, asup- 4 port member attached to the free endof each panel integral with and extending at an obtuse angle to the panel, said support membersjbeing adapted to support the panels, a clamp for each support member, each clamp including a pivot arm hinged to one of the support members and a clamp arm adapted to engage one of the panels and grip an offset master sheet along an edge thereof, each of said "clamps being formed of resilient metal, and a link connecting said clamps, the connection between each clamp and ;the link being between the panel hinge and the -clamp pivot, said panels being angularly inacline'd to each other when said clamps are open, said link pulling the clamps against the panels "when thepanels are moved into straight line ,position, whereby the clamp arms are adapted to grip opposite edges of the master sheet re .siliently and hold the master sheet in flatwise relation to the panels.

5. A rack (for holding an offset master sheet whichcomprises apair of adjoining flat panels,

adjacentredges of said panels normally meeting at a peak and being hingedto each otherma support member extending at an obtuse angle from .the-iree end of each panel, saidsupport members :being adapted tosupport the panels, a clamp .for each support member, each clamp. extending substantially across one of the panels and including a'pivot arm hinged alonga lower side .of "one of thesupport members toswing toward and away from the support member. and a clamp .armadapted to engage one-of the panels, apair of lugs attached to the pivot armof each clamp, each of said lugs extending beyond the support member to which the pivot arm ishinged adjacent a side of the rack, and a pair of links,

each link extending between the lugs of opposite REFERENCES CITED, The following references are of record in th file of thispatent:

UNITED STATES PATENTS Date Number Name 965,887 Flanigan Aug. 2,1910 2,103,617 Gericke Dec. 28, 1937 2,167,695 wahlquistet al. Oct. 17, 1939 

